H, Hennessy on the Distribution of Isothermal Lines. 381 
_ Butif wrepresents the mean longitude of the sun, and P the 
parameter of the earth’s orbit, we should have 
= R2du=/Pat. 
But also 
\ sind = sinisinw, 
‘being the inclination of the equator to the ecliptic: therefore 
above expression becomes 
2 
a Af cot —sin?isin?ududidp 
~ Lf sinisin u sin 4 cos hdudhan | 
the proach of the rectangle, we may take # from o to m, and 4 
m4, to 
whichever of 
Tecelved during a year. 
4. The heat ected Ge the element m(+,—,) from the influ- 
faces of causes, independent. of direct solar radiation, will, as 
already stated, ’ be 
from the coast; it will therefore be a function of .the difference 
of its latitude and that of the nearest point on the coast. If we 
make 2, 2=24, and represent the latitude of the northern 
ays the coast nearest the element of surface by /, we shall 
‘ave for H the proportion of heat received by the element dur- 
$4 year, the expression 
H= (!- 4) 
omy at : 
i taf [3 (in2h, ~sin229)-+2, ~Agl/ ms 2jsin 2udw 
an i icagse 
. i > 2(c0s 24, —cos 22.) sinz sinudu 
annte: Second of these integrals vanishes between the limits, 
fy the m5 may be determined by the properties of elliptic 
Pe a 
j ee tp ORaees meee 
: oVi-sn 2) sin micas 1—sin7i sin 2udu 
=4 £(i), 
